In recent years, the types of devices available for viewing images have increased dramatically. Consumers view images on several different output devices such as monitors, displays, televisions, cameras, printers, and other electronic devices. Whereas the Cathode Ray Tube (CRT) used to be the standard device for viewing images, today a user can also purchase a Liquid Crystal Display (LCD) or a Plasma Display Panel (PDP). The increasing variety of available devices, however, has produced a problem of color uniformity. Because of the mechanical differences between the different types of devices, colors are often displayed in different ways. That is, as the proliferation of available displays becomes more and more visible, the problem of color uniformity becomes more evident.
As such, in the new post-production environment, it has become more and more useful to be able to create color information metadata from, for example, a color transform tool that can be made available in a color management process from capture to post production. That is, as a device prepares to display a color, the display device requires accurate color information metadata to transform (adjust) content color to a desired color space before the device displays the desired color. For example, a visual comparison of a signal on different display types is a current practice in post-production. In such comparisons, a color transform (adjustment) is performed to attempt to match one display to the other or to a desired color space.
One color transformation technique involves the use of a 3-Dimensional lookup table (3D LUT). This technique uses a table defining a corresponding output color for each input color. 3D LUT's can today be automatically generated with available technology. The 3D LUT technique, however, cannot be carried with the content through the workflow (e.g., from capture to post processing) at least because of limitations in available display devices and, as such, the 3D LUT cannot be reused at the display decoding level. That is, the 3D LUT is not practical for an end-to-end design because the 3D LUT does not allow the deconstruction of sequential decisions integral to the 3D LUT and because the processing power associated with a 3D LUT is very intense and would not be practical for currently available consumer displays.
Another color transformation technique involves the use of Color Decision Lists (e.g., the American Society of Cinematographers Color Decision List (ASC CDL)). A Color Decision List (CDL) is comparable to an Edit Decision List (EDL) for representing a film or video edit except that a CDL is directed to color-grading choices. Unfortunately, most CDLs are proprietary to their respective portions of a workflow, which prevents the workflow from being seamless. That is, such a CDL cannot carry cinematographers' choices through the workflow. In addition, these CDLs only implement channel specific 1D LUTs that do not address cross talks between color channels (e.g., hue deviations).